Screw socket



uly 6, 1938. A. E; GRANT 2,124,616

SCREW SOCKET Filed June 29, 1936 ATTORNEY Patented July 26, '1938 1UNITE-b 2,124,616 SCREW SOCKET Albert E. Grant, New York, N. Y.,assignor to Albert T. Otto & Sons, Inc., New York, N. Y.

Application June 29, 1936, Serial No. '87,880

2 Claims.

My invention relates to electrical screw sockets of the type adapted toreceive a standard lamp or screw plug and, more particularly, to thescrew threaded contact shells forming a part of such devices.

It has been usual to form the tubular contact shells in lamp sockets bydrawing them in a die from fiat metal, the resulting structurecomprising a thin tubular member having the walls thereof corrugatedtodefine a thread for receiving the base of a lamp or a male threadedplug member.

I have found that because of the substantial tolerances required, themale threaded member of the lamp or plug frequently does not obtain aproper connection within the socket until the end of the plug memberabuts the central socket contact and is screwed tightly thereagainst todraw the threaded portions into close contacting relation. Thereafter,if for any reason the thread pressure is reduced, as by jarring orvibration, the central contacts Within the socket are not held firmlytogether, with the result that arcing between the central contacts iscommon and frequently the electrical connection is broken entirely.

It is the principal object of my invention therefore to provide a screwcontact shell for lamp sockets in which the male plug member will beembraced and clasped in close contacting relation at all times therebyholding the male member in the socket in intimate contacting relation.

Another object is to provide a screw socket shell for electric lampshaving the foregoing advantages which may be manufactured at low costand employed in place of the standard shells now in general use.Referring to the drawing which forms a part of this specification, I

Figure 1 is a perspective view of a screw socket contact shell embodyingthe features of my invention.

Figure 2 is an elevational view, partly in section, showing a lampsocket embodying my improved screw shell.

Figure 3 is a view similar to Figure 2 illustrating the close contactingrelationship of the parts when a lamp is connected in the socket.

My improved screw socket shell comprises a threaded tube ID of resilientmetal obliquely split from its top to its bottom at H in the directionof the thread. The lower end of the shell is flared outwardly at l2 tofacilitate reception of a lamp or other male threaded contact member andthe upper edge margins are bent inwardly at right angles to form afiange I3. A hole is formed through the flange at IE to receive theusual stud or staple whereby the shell may be secured in the lamp socket20 and connected with 7 one of the current supply wires 2| thereof, theother wire being connected to the contact 3| located centrally in thesocket recess.

The helical thread I4 is of proper pitch to receive the male threadedcontact member of a standard lamp, fuse, or screw plug, but the normaldiameter of the shell is slightly less than the diameter of such malemember and less than the internal diameter of the standard socket inwhich it is carried, substantially as shown in Figure 2. However, whenthe somewhat larger male threaded base 40 of a standard lamp is threadedinto the socket, the split shell is expanded against the resistanceinherent in the resilient metal of which it is formed, being forcedagainst the insulated socket walls 32 and securely embracing andclasping the male member in tight 20 contact, the central contacts 3|and 4| being held in firm abutment at all times.

The angular disposition of the slot ll intersecting the convolutions ofthe thread I4 permits contact between the shell and the male member overthe full circumference of the lat- 'ter.

When the lamp or plug is removed from the socket, the resilient shellresumes its normal undersized condition, so that it may be reused toobtain all of its advantages a larger and indeterminate number of times.

Screw socket shells may be manufactured very economically in my improvedform by drawing an undersized shell from suitable spring metal in theusual manner of manufacture and thereafter splitting it. However, Iprefer to make the device from strip metal, each strip section havingits end edges extending obliquely to the strip and parallel with eachother, the strip being curled into tubular form with its end edgesbrought into close adjacence to define the angular slot ll. When somade, the thread M, the flare l2 and the flange l3 may be imparted tothe strip by die elements carried in the rolls employed to curl thestrip into its tubular form.

However made, the device will be found to provide improved springpressed contact and good mechanical connection.

I claim:

1. In a screw socket, a housing, a contact shell comprising a tube ofresilient metal threaded to receive a standard male threaded contactmemher, said tube having normal diameter less than said member and beingsplit entirely theretube is adapted to be expanded by a male mem 5 perand to resiliently clasp said member in close contacting relation.

2. In a screw socket, a housing, a contact shell comprising a tube ofresilient metal threaded to receive a standard male threaded contactmember, said tube having normal diameter less than said member and beingobliquely split entirely therethrough transversely of its thread,

said tube being secured in the housing at its inner end adjacent and toone side of the split 5 therein whereby the tube is adapted to beexpanded by a male member and to resiliently clasp. 7 said member inclose contacting relation.

ALBERT E. GRANT.

